Communication systems are known to include a system controller, a plurality of base station controllers, a plurality of base stations, and a plurality of subscriber units. In operation, the system controller processes communication requests to and from the subscriber units. For a subscriber unit initiated service request, the particular subscriber unit transmits an inbound signaling word over a control channel to a base station. The base station, which is in the same geographic area as the subscriber unit, transmits the request of the subscriber unit to the system controller. The system controller processes the request and determines whether it can be handled locally or whether it needs to be routed to a communication network. If the request can be handled locally, the system controller processes the request by granting the subscriber unit access to a voice or data communication channel. Having been granted access to the communication channel, the subscriber unit performs the requested service, which may be a telephone call to a wireless or wireline telephone, a data packet transmission, call-waiting, or any other type of radio communication service (including group dispatch).
In wireless communication systems, a majority of communications occur over RF (radio frequency) communication channels between the subscriber units and the base stations. Other communications within the wireless communication systems, however, are just between subscriber units, which method of operation is referred to as talk-around or direct mode. In a talk-around mode, the subscriber units communicate directly to each other over a dedicated RF transmission path. Such a talk-around mode is useful in many situations. For example, construction workers at a particular site would use the talk-around mode to communication with each other locally (i.e., without having to communicate through the system). To enter the talk-around mode, each of the construction workers switch their subscriber units into a talk-around mode via a select mode switch or key pad entry.
While the talk-around mode works well for end-users (e.g. the construction workers), service providers of a shared system (i.e., same communication infrastructure is used by subscriber units of the service providers) often don't provide the talk-around mode option because there isn't a mechanism for monitoring usage of the talk-around mode. Without a mechanism for monitoring usage of the talk-around mode, service providers of a shared system have no means for obtaining revenue from subscriber units for their usage of the talk-around option. Therefore, a need exists for a method and apparatus that allows service providers of a shared system to obtain revenue from subscriber units for their usage of talk-around mode by subscriber units.